Daily Sun: 18 May '07 Sunspot 956 has developed a delta-class magnetic field that harbors energy for X-class solar flares. Credit: SOHO/MDISunspot Number: 30 What is the sunspot number?Updated: 17 May 2007

What's the name of that star? Where's Saturn? Get the answers from mySKY--a fun new astronomy helper from Meade.

SUNSPOT 956: Sunspot 956 continues to grow (movie) and it now has a complex magnetic field that habors energy for X-class solar flares. NOAA forecasters estimate a 5% chance of such an explosion during the next 24 hours. Stay tuned.

SUNSET PLANETS: Photographer Martin Gembec of the Czech Republic calls this a "good sky." The glow of sunset, the planet Mercury, and a whisper-thin crescent Moon:

He took the picture last night while the Moon was passing by Mercury. Consider it a preview: On Saturday night, May 19th, the crescent Moon will pass even closer to Venus, and it is a sight you must not miss. Venus and the crescent Moon will lie barely 1o apart, forming a brilliant and unforgettable pair. When the sun goes down on Saturday, be outside looking west: sky map.

GALACTIC FOSSIL: "The scientific community is still buzzing about the discovery of HE 1523-0901, a 13.2 billion year old star which formed a mere 500 million years after the Big Bang," says Anthony Ayiomamitis of Athens, Greece. "I took this picture of the star on May 13th."

Indicated by the arrow, HE 1523-0901 is 11th magnitude and located in the constellation Libra. It looks much like any other star in the area--but it is special. HE 1523-0901 is one of the oldest stars in the Milky Way, perhaps one of the oldest in the Universe, and by studying it astronomers may be able to learn new things about the genesis of our galaxy.

A team of astronomers led by Anna Frebel of the University of Texas dated the star using a technique similar to carbon-14 dating. HE 1523-0901 contains radioactive elements uranium and thorium. (These elements leave their imprint on the star's spectrum, which is how they can be detected and measured.) By comparing the abundance of uranium and thorium to other elements in the star which do not decay, the researchers were able to make six independent estimates of the star's age, and they all agreed: 13.2 billion years. Click here to read the original research.

Potentially Hazardous Asteroids (PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time.

Notes: LD is a "Lunar Distance." 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach.

Essential Web Links

NOAA Space Environment Center -- The official U.S. government bureau for real-time monitoring of solar and geophysical events, research in solar-terrestrial physics, and forecasting solar and geophysical disturbances.

Atmospheric Optics -- the first place to look for information about sundogs, pillars, rainbows and related phenomena.